Here is where you can download the driver. Make sure that you have the 32bit version of Ubuntu, because this a 32bit driver only.
Once downloaded follow the following:
A. RUNNING THE GUI INSTALLER SCRIPT IN THE TERMINAL
Open up terminal, just press Ctrl+Alt+T on your keyboard to open Terminal. When it opens, run the command(s) below:
Extract the zip file
Use the following command to install the driver
Follow the instruction in the installation screen.
B. RUNNING THE GUI INSTALLER SCRIPT
Do not attach the printer via USB to the Linux machine.
Extract the zip file.
Run the installer script file by double-clicking on the file icon and then click the "Run in Terminal" button or run the script file via command-line.
Follow the instructions in the installer screen.
Installation instructions Source:Lexmark